The invention relates to a dispensing device for pourable, especially powdery material. The dispensing device has a charging chute, a vertical filling pipe adjoining the lower end of the charging chute, and a closing cone arranged at the lower end of the filling pipe. The closing cone is displaceable in the longitudinal direction of the filling pipe by a shaft. The closing cone, in its open position, provides an annular gap at the lower end of the filling pipe. The closing cone, in its closed position, rests against an annular face of the lower end of the filling pipe.
When filling bags with pourable material, it is desirable, on the one hand, to fill the bags quickly in order to increase the capacity of the filling plant. On the other hand, it is necessary to ensure accurate dispensing. Accuracy is important since fill quantities below the nominal value are not permissible and fill quantities above the nominal value are uneconomical. The two requirements, a rapid filling operation, on the one hand, and accurate dispensing, on the other hand, are incompatible with one another. This is due to the fact that rapid filling requires large quantity flows and accurate dispensing utilizes small quantity flows to achieve satisfactory results.
Therefore, according to the state of the art, bags are rapidly filled with large quantity flows, up to a certain level, 90 to 95%, of the nominal quantity. Subsequently, a small quantity flow enters the bags to ensure an accurate filling level which is only a few percentage points in excess of the nominal quantity of 100%.
To achieve the above results, it is possible, in addition to a first filling device for dispensing an approximate quantity, to use a dispensing device which can only release a fine flow of material for fine dispensing. Alternatively, a dispensing device with a filling device for dispensing approximate quantities which allows the setting of differently sized apertures for approximate and precision filling purposes can be used.
One problem in connection with fine dispensing is that powdery materials have a tendency to form bridges in narrow exit apertures. The bridges can prevent the flow of material even in the case of high material loads. Especially, if the material has a sticky consistency which may occur in the food industry with material such as cocoa powder, milk powder or the like, it is practically impossible to have reliable flow conditions in a free flow from a narrow aperture fine dispensing device.